Definition: In this task, you are given an input list A. You need to convert all the alphabets in the list with a number representing their position in the English alphabet. E.g., replace A by 1, B by 2, a by 1, b by 2, and so on.
Input: ['6727', 'R', '3613', 'l', '5399', 'k']

6727, 18, 3613, 12, 5399, 11